Don't forget this only applies to domestic vacuums Tel, you can still buy industrial ones.i'd love to try a 500watt vac. on my wall chaser. my henry 1000watt struggles to get more than 75% of the dust.
Just had a look on the Henry web site. Seems they do 3 basic domestic vacuums the 160, 200 and 240. The largest the 240 has a 620w motor.